Mechanical underfeed stoker



Oct. 11, 1932. v. s. LEACH MECHANICAL UNDERFEED STOKER Filed Aug. 24, 1929 3 Sheets-Sheet 1 ml Mu l" YIIIII/IIIIIIIII/IIIIIIIIIIIIIIIIIIIIIIII! YIIIIIIlIIlIIIIIII/IIIIIIII IIIII III IIIIIII W;

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MECHANICAL UNDERFEED STOKER Filed Aug. 24, 1928 2 Sheets-Sheet 2 W Verna): G leach Patented Get. 11, 1932 ,..UN.ITED STATES PATENT, OFFICE VERI\TON G. LEACH, OF CHICAGO, ILLINOIS, ASSIGNOR TO MODERN COAL BURNER- COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS YMECHANICAL UNDERFEED STOKER Application filed August 24, 1929. Serial No. 388,065.

This invention relates to improvements in mechanical underfeed stokers and more particularly in the. construction of the tuyre blocks. g

It is an object of this invention to provide an improvedconstruction of tuyere blocks for use in mechanical underfeed stokers and adapted to provide an eflicient dlstrlbution of air to the fire bed.

' It is a further important object of this invention to provide a tuyere blockof such constructionthat there is a proportionate distribution of air even should the ends of the tuyre block become burned off for a considerable distance.

Other and further important objects of this invention will be apparent from the disclosures in the specification and the accompanying drawings.

This invention (in a preferred form) is illustrated in the drawings and hereinafter more fully described.

On the drawings:

Figure 1 is a transverse sectional view of a furnace setting illustrating the arrangement of tuyere blocks embodying the principles of this invention.

Figure 2 is a top plan view of the mechanical underfeed stoker unit.

Figure 3 is an enlarged side elevational "view of a tuyere block.

Figure 4 is a bottom plan view of the same. Figure 5 is an end elevational view of a pair of tuyere blocks.

Figure 6 is a sectional view taken substantially on line VIVI of Figure As shown on the drawings: w

The reference numeral 1 indicates generally afurnacehousing comprising lower walls f masonry and upper side walls 3. Partly within said housing 1 is mounted a mechanical underfeed stoker indicated as a whole by the reference numeral 4. Said stoker 4 comprises-a hopper 5 into which the coal or other fuel is charged and a worm conveyor 6 extending from the bottomof said hopper 5 through a conduit 7 into a retort 8. The screw conveyor 6 is adapted to be driven by any suitable means, such as the motor 9 and reducing'mechanism 10, for conveying the crushed coal into the retort 8.

Said retort 8 comprises a casting formed with side walls 11 and 12 provided with parillell, flangedupper edges 13 and 14, respcc: we y.

Tuyere blocks 15 of my invention are adapted to be mounted upon the upper flanged edges 13 and 14 and for this purpose are provided with a lower lug 16 in the form no of a hook for detachably engaging said flanged edges 13 and 14. The outer base portions of said tuyere blocks 15 rest upon and are supported by angle irons 17 or other suitable supporting means. A groove 50 is formed transversely of each of said tuyere outer base portions to receive cement or the like for forming an air-tight joint with the angle iron support, should it be desirable to put an air seal from the angle iron 17 down to the floor. Each of said tuyere blocks 15 is furtherformed with a groove 18 extend ing transversely along its outer upper face for receiving the downturned lateral edge 19 of a dead plate 20. Other dead plates 21 and 22 are suitably associated therewith and mounted upon the masonry walls 2 to form a relatively air-tight supporting surface for the burning coal from which the clinkers and ash may be removed.

A front plow plate 23 and a rear plow'plate 24 preferably formed in sections, form the end walls of the built-up retort. I

As thus illustrated in Figures 3 to 6 inelusive, each of the tuyere blocks 15is formed of a single casting having an intermediate vertical web 25, a vertical inner edge 26 flanged for a portion of its height as at 27 and outwardly and downwardly sloping flanged edge 28, the flanged portions in every case ex: tending equally on each side of the intermediate web portion 25. I I

A plurality of ribs 29 and 30 are formed on said intermediate web portion 25 to extend from the inner upper edge 26 to the near outer lower portion of said web 25. Said ribs 29 and 30 are symmetrically formed on each side of the web 25. Said ribs 29 a'nd '30, furthermore, are equally spacedfrom each other and from the top flange 28 and the top lUU In the event that it is desired to -make a" two-opening tuyere rather than a threeopening, as shown, rib 30 may be omitted entirely and rib 29 spacedequally from the. top flange 28 and the top of the inner edge flange 27.

In order to prevent the escapeof air between abutting tuyere blocks below the openings 38, the lateral edges ofthe-flanges 27'ware'provided with grooves [46 adapted to be filled' with a suitable cement and thus render the joints airtight.

When the tuyere blocks are aligned in position, as shown in Figure 5, corresponding adjacent grooves 31,32 and 33 inadjacent tuyere blocks-form passages 36, 37 and 38, respectively, of generally rectangular cross section for the flow of air into the fuel bed;

' As arranged above the side walls of the retort 8, the vertical inner ed ges 26 of the tuyere blocks includingv their lower flanged inner edges 27 ,forni avertical continuation of the side walls 11 and 12 of saidretort. The mass of coals accordingly builds up, between the vertical walls 39 and 40 formed by the inner faces of said tuyere blocks and overflows down over the outwardly" and downwardly inclined wal1s 41 and 41- formed by the abutting flanged edges 28 of said tuyere blocks.

, Air'is supplied in the usual manner underneath-the dead plates and flows upwardly through the passages 3l, 32'and 33 between the 'tuyere blocks. Because of thetapered formation of the ribs 29 and 30 and the gen.- eral curvature and arrangementof said ribs and the flanged edges 27- and 28, little resistance is offered to the flow of air through said tuyere blocks into the fuel bed. The ar rangement and shape. of'the tuyere blocks 1 are such thatthehot zone ofthe fuel bed does not extend down into the retort proper, sothat' the body of the retort is below the hot zone and is not subject to such'high temperatures j as would" cause. expansion strains. Also, the ribs and fins ofthe tuyere blocks serve as heat conductors to dissipate the heat into the main cooling web, the web 25. f

Consequently there is little tendency'for thetuyere blocks to become over heated, but it should be noted thatif the top front-faces ofthe tuyere blocks should become burned awayafter long continued use, the relative size and {spacing of the air passages'36, 37, and '38 remain substantially constant owing to the-fact that the upper curved'portions 42, 43 and 44 of the flanges 28 and ribs 29and .30,

respectively, are formed along substantially concentric arcs. Even the upper edge of the front flange 27 is curved as at 45 in conformity with the curves 42, 43 and 44-.

The cement seals between the tuyere blocks themselves and between the tuyereblocks and supporting surfaces eliminate the possibility of air leaking into the fuel bed within the built up retort so thatall of the air is deli v ere ld through thepassages 36, 37 and 38, well'up toward the top of the tuyere blocks, with the result that the fire line is kept above the top of the retort proper.

There is thusprovided a substantiallyradial distribution of air throughout the fuel bed, The backward slope of the tuyere blocks is such that the fuel bed builds up above the retort and tuyeres in the, form of a fairly flat, curved mound, all outside portions of which are substantially equi-distant from the air inlets, with the result that-the airdoes not tend to follow localized channels pug isevenly distributed throughout the fuel e The downward and backward slope of the tuyere blocks aids to carry the slag down onto the dead plates, from which it is drawn or pulled out of the furnace.

Benewal of a tuyere block is facilitated by the arrangementand construction of tuyeres e and dead plates in that it is only necessary in order toremove a burned out tuyere to lift out one of the dead plates 20. i

I am aware that many changes may be made and numerous details. of construction may be varied through a wide range without departing from the principles of this invention, and I, therefore, do not purpose limiting the patent granted hereon otherwise thannecessitated by the prior art. I claim as my invention: v

1. A tuyere block for a single-retort stoker having parallel spaced walls, said block being a substantially quadrantal member havin g a web with a lower edge adapted to rest on a wall of the stoker, a vertical inner face including a spacing flange extending from the lower edge of the web toa point more than half way up the inner edgeof said web, a curved flanged edge defining the con vex edge of the. block and extending from the top of the inner edge of the webto the lower edge of the web, and spaced inwardly converging curved ribs on the webbetw'een the flange on the inner edge of the web and the said curved flanged edge and havingv ends te'rminatingat the inner edge of the web in spaced apart relation to saidflanges. V In combinationyin, a single retort stoker, a'suppoiting'wall', asubstant-ially quadrantal tuyere blockliaving a web with a base edge on the wall, an inner edge having a flangedportion extending from said base edge for a substantial distance along said inner edge, a flanged curved edge defining the nace stoker having a wall, said block being substantially quadrantal in shape, and having a web with a flanged curved edge defining the convex edge of the block and extending from its base edge to the top of its vertical inner edge, the said block being adapted to be seated on its base edge on a wall of the stoker, a flanged edge extending from the base of the web along its vertical inner edge for a distance more than half way along the inner edge, spaced and inwardly converging curved ribs on the web between the flange on the vertical inner edge and the curved edge, said ribs extending from the vertical inner edge of the web downwardly and outwardly, and having a depth substantially equal to that of the curved flange edge and being spaced apart a distance substantially equal to their rib depth fora portion of their length adjacent the vertical inner edge so that they define discharge orifices with adj acent blocks of substantially undiminished area until a substantial portion of the inner vertical edge of the web has been burned away.

4. A tuyere block for a single-retort stoker, having a wall capped by an angle-iron and having dead plates on the wall, said block being substantially quadrantal in shape and having a web with a base edge for seating on the wall and a hook projecting below said base edge adapted to engage an angle-iron on the wall, the said web also having a flanged curved edge defining the convex edge of the block and extending from its vertical inner edge to its base edge and forming a part of the latter edge, the said curvededge having a recess formed therein near its end adjacent the base edge of the web adapted to receive a portion of a dead plate to hold the block clamped seated on the wall of the retort.

5. A tuyere block for a single-retort stoker having a wall with a dead plate and an angle iron thereon, said block being substantially quadrantal in shape and having a web with a base edge for seating on the wall, an integral hook projecting downwardly from the base edge adpated to engage an angle iron, the said web having a flanged curved edge defining the convex edge of the block and extending between the top of its inner vertical edge and its base edge, said curved flanged edge being reversely directed at its lower end to provide an outwardly and upwardly extending toe adapted to engage a dead plate.

In testimony whereof I have hereunto subscribed my name at Chicago, Cook County,

Illinois.

VERNON G. LEACH. 

